DEAR DR. DONOHUE: Night sweats not usually a sign of illness

Published Thursday, September 15, 2005

DEAR DR. DONOHUE: I would love you to address the problem of night sweats. I live in a climate that is cool at night all year round, but I drench my nightgown and bedclothes every night. What's causing this? -- A.K.

ANSWER: Body temperature has a normal daily variation. In the early-morning hours -- around 3 a.m. -- body temperature is at its lowest. That's normal. For the body to achieve that lower temperature, it produces more sweat that evaporates for cooling. Some people have an exaggeration of this process and pour out sweat that soaks them and the bed.

Furthermore, at night, urine production slows. The body still wants to get rid of fluid, and it does so by increasing its sweat output.

Both of these are normal phenomena.

Check your room's humidity. It might be too high for the sweat to dry. A dehumidifier could be the answer.

Alcohol and nicotine promote sweating. Don't drink any alcohol after 5 p.m., and if you smoke, stop.

I must include the list of illnesses that can be linked to night sweats. Lymph-node cancer, including Hodgkin's disease, is one. Diabetics tend to sweat more at night. An overactive adrenal gland or an overactive thyroid gland promotes night sweats. Hidden infections are another possible cause. TB is also cited as producing night sweats, but in truth it rarely does so. Other infections can. Although these illnesses are not usually found to be responsible for night sweats, you should mention this to your doctor so he or she can consider them.

If you take your temperature when you wake up sweating and find that it is normal, that's a piece of evidence that speaks in favor of the innocence of your night sweats.

DEAR DR. DONOHUE: What is a congenital heart defect? Is that a blue baby? My niece just gave birth to a baby boy, and my sister told me that he has a congenital heart defect but is not blue. What's the significance of this? -- P.P.

ANSWER: "Congenital heart defect" covers too much ground to provide you with a satisfactory answer. It indicates that during development in the uterus, something went amiss during the maturation of the heart. Such things include heart-valve problems, holes between the chambers of the heart, abnormal connections between the heart and blood vessels, and abnormal wiring of the heart that produces unusual heartbeats.

Some congenital heart defects correct themselves in time. Some are so minor that they need no correction. Others are major and call for surgical intervention.

A blue baby is the result of a congenital heart defect where blood returning to the heart bypasses the lungs and doesn't get the oxygen it should. Blood without a sufficient supply of oxygen has a dark-blue color.